Abstract
OBJECTIVE: To fulfill the requirements for bariatric surgery, patients often need to participate in mandatory preoperative lifestyle interventions. Currently, the efficacy of multi-month preoperative lifestyle intervention programs on body mass index (BMI) reduction from the start of the program (T0) through the immediate preoperative time point (T1) to 1 year post-surgery (T2) and how the amount of preoperative BMI reduction affects postoperative outcome (T1 to T2) is unclear. The aim of this meta-analysis was to analyze the effects of preoperative lifestyle interventions on BMI 1 year post-surgery. METHOD: A systematic literature search was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. Randomized controlled trials that implemented preoperative lifestyle interventions lasting 1-8 months before bariatric surgery were included. The BMI of the intervention group was compared with that of a control group before participation in the preoperative lifestyle interventions (T0), after completion of the program before surgery (T1), and 1 year post-surgery (T2). Finally, the impact of successful BMI reduction at T1 on BMI at T2 was analyzed. RESULTS: N = 345 patients derived from 4 studies undergoing preoperative lifestyle interventions reduced their BMI at T1 by 1.5 units compared to the control group (95% CI: -2.73, -0.28). One year post-surgery, both groups had lost comparable BMI points. The influence of reduced BMI at T1 on weight status at T2 is unclear due to the lack of available studies. Other endpoints and subgroup analyses were rarely examined. CONCLUSIONS: Preoperative lifestyle interventions reduce BMI before bariatric surgery more effectively than usual care. These differences are not detectable 1 year post-surgery. Although a short-term energy reduction period before surgery is clearly important to minimize surgery risks, it is currently unclear whether, and if so, under what circumstances, participation in a preoperative lifestyle intervention is beneficial.